Automatic sear-releasing mechanism for firearms



Feb. 15, 194-9. D M. WHLLIAMS AUTOMATIC SEAR-RELEASING MECHANISM FOR FIREARMS 4 SheetsSheet 1 Filed July 21, 1945 Mme/wok DAvm P1. WILLIAMS WWM,-M

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AUTOMATIC SEAR-RELEASING MECHANISM FOR FIREARMS Filed July 21, 1945 4 Sheets-Sheet 2 Feb. 15, 1949. D. M. WILLIAMS AUTOMATIC SEAR-RELEASING MECHANISM FOR FIREARMS lA/IENTOR M A H M w M D M D 147'7'0/ENEVS Feb. 15, 1949. D. M. WILLIAMS I fim fi AUTOMATIC SEARRELEASING MECHANISM FOR FIREARMS 4 Sheets-Sheet 4 Filed July 21, 1945 l T om QW .QW

-iti 1/ ELL-i14ififffinifffif?fin/171E144i M! ww m Mk WTQFL mm J m bdrm Patentecl Feb. 15, 1949 UNITE AUTOMATIC SEAR-RELEASING MECHANISDI FUR FIREARMS David M. Williams, New Haven, Conn, assignor to 01in Industries, Inc, New Haven, Conn a corporation of Delaware Application July 21, 1945, Serial No. 606,320

.6 Claims.

The present invention relates to improvements in self-loading firearms and relates more particularly to self-loading firearms of the type which may be selectively utilized either as fullautomatic or as semiautomatic weapons, i. e., weapons which will either automatically reload and repeatedly discharge as long as the trigger is held in its pulled position, or which will automatically reload but require the normal operation of the trigger to effect the discharge of each shot.

One of the main objects of the present invention is to provide a superior self-loading firearm of the type which may be utilized either as a full-automatic or a semiautomatic firearm and which will combine reliability of functioning with economy of manufacture and ease of maintenance.

Another object of the present invention is to provide a superior self-loading firearm of the type above referred to, having a simple, reliable and eifective arrangement of parts whereby the firearm may be readily converted from semiautomatic tofu'll-automatic operation and vice versa. A further object of the present invention is to provide an automatic self-loading firearm having a superior construction and arrangement of parts whereby the rate of fire may be kept at a relatively-low rate as is sometimes desired to meet certain requirements.

A still further object of the present invention is to provide a. superior full-automatic firearm having a construction and arrangement of parts whereby a wide range of rates of fire may be provided for ,without requiring the i e-designing of the weapon.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a broken view in side elevation of the portion of a firearm-structure adjacent the receiver and with the stock omitted, the parts being shown in the positions which they assume at the instant of discharge and when the adjustment is made for full automatic fire;

Fig. 2 is a broken View partly in side elevation and partly in the vertical central longitudinal section of the portion of the firearm located immediately forwardly of the portion illustrated in Fig.

Fig. 3 is a top or plan view of the portion of the firearm shown in Fig. 1 and with the rear portion of the action-slide shown in horizontal section;

Fig. 4 is a broken view of the left side of the rear portion of the firearm-structure but on a smaller scale than the preceding figures;

Fig. 5 is an underside view of the showing of Fig. 4 but with the trigger-plate unit omitted and with the parts shown in the positions which they assume as the action-slide is moving forwardly following the discharge of the firearm and with the timing-bar about to be disengaged from the action-slide;

Fig. 6 is a similar view but showing the timing bar after its release and at the limit of its rearward travel and at the instant of the discharge of the firearm;

Fig. 7 is a view similar to'Figs. 5 and 6 but showing the action-slide retired to the limit of 0 lug 2! of the breech-bolt l8.

its rearward movement immediately following the discharge of the firearm as a result of the action illustrated in Fig.6;

Fig. 8 is a broken view in vertical central-longitudinal section of the rear portion of the firearm-structure and showing the trigger held in its pulled position and the hammer as held in its cocked position by the secondary-sear;

Fig. 9 is a. view in rear elevation of the showing of Fig. 8;

Fig. 10 is a perspective view of the selectorlever, detached; 1

Fig. 11 is a similar View of the sear-actuating lever;

Fig. 12 is a perspective view of the timingbar, detached;

Fig. 13 is an underside view similar to Fig. 6, but showing the forward end of the timing-bar swung into its retired position to thereby convert the firearm for semiautomatic fire; and

Fig. 14 is a broken detail sectional view through the left side-wall of the receiver and through the timing-bar and timing-spring, taken on the line I 4-l4 of Fig. 4.

The particular gas-operated self-loading firearm illustrated in the accompanying drawings and chosen for purposes of making clear one form of the present invention, includes in the main, a

receiver 95, a. barrel 5, a trigger-plate unit H;

a breech-bolt l8 and an action-slide 19.

The breech-bolt 18 above referred to is mounted in the receiver it with capacity for both longitudinal reciprocation and lateral oscillation. The said breech-bolt is formed adjacent its forward end with two locking-lugs 20 and 2d respectively offsetting from the breech-bolt in substantially diametrically-opposite directions. The left side-wall '22 of the receiver I5 is formed with a, forwardly-facing locking-abutment 23 which is adapted to be engaged by the rear face of the locking-lug 20 of the breech-bolt l8. Similarly, the right side-wall Ed is formed with a forwardly-facing locking-abutment 25 which is adapted to be engaged by the rear face of the lockingnote that the surfaces of the cam-recess 21 coact with the surfaces of the operating-lug 26 in such manner thatwhen the action-slide I9 is moved rearwardly, the breech-bolt I8 will first be caused to turn in a clockwise direction (as viewed from the front) to disengage the lockinglugs and 2| respectively from the lockingabutments 23 and 25 of the receiver I5. Following this unlocking movement of the breech-bolt, the coaction of the surfaces of the cam-recess 21 with the operating-lug 26 will then effect the direct rearward axial movement of the breechbolt I8. Conversely, when the action-slide I9 is moved forwardly (following the above-described rearward movement thereof), the coaction of the surfaces of the cam-recess 21- with the operating-lug 26 will first draw the breech-bolt I8 forwardly until such time as the respective rear faces of the locking-lugs 20 and 2| thereof register with the locking-abutments 23 and 25 of the receiver I5, whereupon the breech-bolt will be turned transversely in a counterclockwise direction to again lock the breech-bolt, in its breechclosing position.

The action-slide I9 above referred to includes a relatively-slender bar-portion' 30 formed integral with and extending longitudinally of the firearm structure between the rear portion '28 thereof and a crosshead 3| at the extreme for-. ward end of the action-slide. The said barportion 30 constitutes the major portion of the length of the action-slide I9 and reciprocates longitudinally along the right side of the receiver I5 and the barrel I6.

The crosshead 3| above referred to extends beneath the barrel I6 and has its forward face normally engaged with the rear face of the stem 32 at the rear of a piston generally designated by the reference character 33, as is especially well shown in Fig. 2. The said piston also includes a relatively-large-diametered head 34 located at the forward end of the piston and reciprocating in a rearwardly-opening pistonchamber 35. The piston-chamber 35 just referred to is formed in a cylinder-lug 36 formed integral with and depending from the barrel I6 at a point slightly forwardly of the front end of the receiver I5. The stem 32 of the piston 33 extends rearwardly through a ring-like stopmember 31 which is threaded into the rear end of the piston-chamber 35 and which is adapted to have its forward face engaged by the rear face of the head 34 to limit the rearward travel of the piston 33 as a whole.

Extending forwardly and upwardly from the front end of the piston-chamber 35 is an inclined gas-passage 38 which intersects the bore 39 of the barrel I6, as is shown particularly well in Fig. 2.

For the purpose of yieldingly holding the action-slide I9 in its forward position and hence also serving to hold the breech-bolt I8 in its 4 forward or breech-closing position, a helical breech-closing spring 40 is employed; The said breech-closing spring has its rear portion located in a longitudinal spring-passage 4| formed in the lower portion of the right side-wall 24 of the receiver I5, as is shown in Fig. 1. The rear end of the breech-closing spring 40 thrusts rearwardly against a plunger 42 mounted for reciprocation in the rear end of the spring-passage 4|. The rear end of the said plunger 42 bears against the right arm 43 of a sear-actuating lever generally designated by the reference character 44, as is especially well shown in Figs. 5, 6 and 7. The said sear-actuating lever is of substantially-U-shaped form and includes a left arm 45 whichis longer than the right arm 43, as is especially well shown in Fig 11. On its outer edge, the left arm 45 is formed with an L-shaped retaining-finger 46 having its upper end inwardly directed and entered into a retaining-groove 41 formed in the left side-wall 22 of the receiver I5 adjacent the lower edge of its rear portion, as is illustrated in Fig. 9.

The major portion of the sear-actuating lever 44 is located adjacent the under face of the rear portion of the receiver I5, and is mounted in the location referred to for pivotal movement by means of a pivot-pin 48 extending upwardly into the adjacent portion of the right side-wall 24.

The tension of the breech-closing spring 40 applied against the forward face of the right arm 43 of the sear-actuating lever 44 serves to normally hold the latter in the position in which it is shown in Figs. 5 and '7 in which the forward face of the left arm 45 is in engagement with a rearwardly-facing stop-abutment 49 formed on the left side-wall 22 of the receiver I5 adjacent the rear end thereof, as is especially well shown in Fig. 4.

At its central portion, the sear-actuating lever 44 above referred to is formed with a downwardly-extending finger 5!] which is adapted to engage with the upper end of a secondary sear 5| as shown in Fig. 8, to swing the said secondary-sear rearwardly under circumstances as will more fully hereinafter appear.

The said secondary-sear 5| fits into a central longitudinal recess 52 formed in the upper portion of a trigger generally designated by the reference character 53. Both the said secondarysear 5| and the said trigger 53 are mounted for pivotal movement upon a pivot-pin 54 extending transversely across a recess 55 in the rear portion of the trigger-plate unit I1, as is especially well shown in Fig. 8.

. The secondary-sear 5| above referred to'has an upwardly-extending arm 56 and is urged in a direction required to swing the said arm forwardly by means of a helical sear-spring 51. The said sear-spring'is mounted in an upwardly-opening spring-pocket 58 formed in the rear portion of the trigger 53 and opening upwardly into the bottom of the recess 52 in the latter, as is particularly well shown in Fig. 8. The upper-end of the searspring 51 thrusts upwardly upon the rear portion of the secondary-sear 5|.

On its forward upper portion, the arm 56 of the secondary-sear 5| is provided with a downwardly-facing cocking-abutment 59 which is adapted to releasably engage an upwardly-facing cocking-abutment 60 formed at the rear of an offsetting-arm 6| integral with and rearwardly projecting from the upper portion of a hammer generally designated by the reference character 62, The said hammer has its lower end extended intohthe forward portion of the recess 55 in the trigger plate unit 1 1 and pivotally mounted therein by means of .aitransverse hammer-pin S3. The forward upper portion of the hammer '62 is adapted to strike and drive forwardly a firingplunger 64 mounted for reciprocation in an axial direction in .the breech-bolt I8. The rear end of the said firing-plunger normally projects slightlyzlbeyond:..the. rearend ofthe breech-bolt l8, and when driven forwardly by the hammer 62 as described, the said firing-plunger effects the discharge ofthe firearm ina manner well known in the art.

On its forward lower portion opposite its cocking-abutment, the'arm 6| of the hammer 62 is provided with can upwardly-facing cocking-abutment 65 which isadapted to engage with a downwardly-facing cocking-abutment 66 formed at the .upper end of a scan-arm 6'! projecting upwardly from the forward portion of the trigger 53 before referred to; as will be apparent by reference to Fig. 8 in particular.

The trigger 53 is yieldingly urged to turn about the pivot-pin 555 as a center in such direction as -to swing its finger-piece forwardly and to swing its seararm 67 rearwardly, by means of a helical trigger-spring B8. The upper portion of the said trigger-spring isaccommodated in a shallow downwardly-opening spring-pocket $9 formed in the forward under portion of the trigger 53, while the lower end of the said spring engages with an adjacent upwardly-facing surface of the triggerplate unit H.

The upper portion of the hammer 62 above referred to is urged to swing forwardly by means :of a helical hammer-spring it, which action is :releasably restrained by the cocking-abutments 59 or fifi'respectively of the secondary-sear 5| and the trigger 53, all in a manner as will more fully hereinafter appear.

In the lower portion of its left side-wall 22, the receiver I5 is formed with a longitudinal T- shaped guide-groove H opening through the outer face of the said side-wall. At its forward end, the guide-groove H intersects the forward end of the receiver and at its rear end intersects the stop-abutment 139 at the rear of the receiver and with which the left arm 45 of the sear-actuating lever 4 normally engages. Mounted for lengthwise reciprocation in the guidegroove H is the rear portion of what, for convenience of description, maybe designated as a timing-bar (2. At its rear end, the timing-bar 12 is formed with an upwardly-extending retaining-finger 13 and a vertically-aligned downwardly-extending retaining-finger "M respectively extending into the upper and the lower undercut. portions of the guide-groove H in the receiver E5. The said timing-har is also formed with a second downwardly-extending retaining-finger 15 which extends into the lower undercut portion of the guideroove "H and, in a sense, acts as a fulcrum-point, in a manner as will hereinafter appear, as well as discharging the function, jointly with the retaining-fingers 13 and i l, of retaining the timingbar 12 against outward lateral displacement from the guide-groove H.

'Mounted in the upper undercut portion of the guide-groove I! in the receiver i5 is a helical timing-spring 18 which thrusts at its rear end against the forward face of the upwardly-extending retaining-finger '53 of the timing-bar l2 and which thrusts at its forward end against the cylindrically-contoured stem 17 of a selectorlever "generally designated by the reference character 'l8, asi's especially well .shown in Figs.'4 and 14.

The selector-lever l8 above referred to includes, in addition to its stem "i1, aradially-ofi'setting finger-piece i9, as isespecially well shown in Fig. 10. The said finger-piece l9 restsagainst the uppersurface of the forward portion of the left side-wall 22 of the receiver [5, while thestem "I thereof extendsdownwardly into a cylindrically-contoured socket 8!]- also. formed in the said left side-wall 22 and extending downwardly to a-point adjacent the extreme lower limit of the longitudinal guide-groove "H, as is shown in Fig.4.

At its lower end, the stem 1'! of the selectorlever :13 is formed with a downwardly-extending eccer" fingerat which is adapted in a manner as will hereinafter appear, to engage with the inner face of the adjacent portion of the timingbar in to outwardly flex the forward portion thereof, asillustrated in Fig. 13 and for purposes as will more fully hereinafter appear. As indicated in the Figs. 3 and 4, the upper portion of the stem f? is engaged by a detent-plunger- 82 mounted for reciprocation in the left s'ide-Wal1'22 and urged forwardly into engagement with the stem i'i'by a helical detent-spring 83. The function of the said detent-plunger 82 is to yieldingly hold the selector-lever 7-8 in either of its two rotational positions, as will be hereinafter described.

At its forward end, the timing-bar T2 is formed with an inwardly-projecting hoolr-generally-desighated by the reference character 84 and including a forwardly-and-outwardly-inclined releasing surface 85 and a rearwardly-facing latchingabutment 86. The latching-abutment 86 just referred to is adaptedto engage with the forward face of the left side of the crosshead 3| of the action--s'lide i9, as is illustrated in Fig. 5. The sloping releasing-surface 85 of the hook 84 of the timing-bar l'2 is adapted on occasion, to engage with a forwa-rdly-and-outwardly-sloping releasing-surface 8? formed on the left rear corner of the cylinder-lug 36, as is especially well shown in Fig. 5 and for purposes as will hereinafter appear.

From the foregoing it will be observed that the timing-spring it constantly urges the timing-bar i2 rearwardly, to thus engage the rear end of the latter with the forward face of the left arm 45 of the sear-actuating lever 44, It is to be further noted that the'effective force of the said timingspring on the lever it is materially less than the effect of the breech-closing spring 40, despite the fact that the latter spring acts on the lever 44 at a point closer to its pivot-point than does the timing-spring it. Thus, under ordinary conditions, the breech-closing spring 41) has sufficient thrust to. normally hold thesear-actuating lever ie in suchjposition that its left arm 45 is against the stop-abutment it, of the leftside-wall 22 and against the rear end of the timing-bar 12, despite the tension of the timing-spring 16.

Full-automatic operation.

For purposes of description, let it be assumed that the marksman wishes to have the firearm function as a full-automatic firearm, i, e., continue to discharge the contents of a magazine as long as. the trigger '53 is held in its pulled position.

Under the conditions above referred to, the marksman will swing the selector-lever 78 so that its finger-piece i9 is directed forwardly as is shown by full-lines in Figs. 1, 3 and 4 to thereby swing its eccentric-finger BI into its innermost position. This movement of the said finger will permit the forward portion of the timing-bar I2 to spring into its inward position, as is shown especially well in Figs. 5, 6 and '7.

, It may further be assumed that the firearm has lust discharged a cartridge located in the rear end of the bore 39'of the-barrel I6. 1

Now under the circumstances above described, gases from the just-fired cartridge will pass downwardly through the gas-passage 38 in the cylinder-lug 3B and will impinge against the forward face of the head 34 of the piston 33. The impingement of gases just referred to will drive the said piston rearwardly until the rear face of its head 34 engages with the forward face of the ring-like stop-member 31. The relatively-short rearward movement of the piston 33 will be sufficiently violent to cause thestem 32 of the said pistonto drive the entire action-slide I9 rears wardly against the tension of the breech-closing spring 48 from the position in which it is shown in Figs. 1, 2, 3 and 4 to its rearmost position, as shown in Fig. 7.

' Theinitial portionof the rearward movement of the action-slide I9 as above described, will cause the surfaces of the cam-recess 21 in the enlarged rear portion 28 thereof, to coact with the operating-lug 26 of the breech-bolt I8, and effect the clockwise turning movement (as viewed from the front) of the said breech-bolt. The turning movement of the breech-bolt as just described will disengage the rear faces of its lockinglugs 20 and 2| from; the locking-abutments 23 and 25 of the receiver I5, to thus unlock the breech-bolt.

Following the unlocking movement of the breech-bolt as just above described, the continued coaction of the surfaces of the, cam-recess 21 of the action-slide I9 withtheoperating-lug 25 of the breechbolt, will slide the said breech-bolt L rearwardly to effect the extraction and ejection of the just-fired cartridge, in a manner Well known in the art.

During the rearward travel of the action-slide I9, the left side of its cross-head 3| will engage with the releasing-surface 85 of the fiexible timing-bar I2 to thus spring the forward end of the timing-bar outwardly. Ultimately the cross-head 3| will move rearwardly of the hook 84 so that the forward portion of the timing-bar may spring inwardly as shownin Fig. '7. i It will be noted that when the parts are in the positions shown in Fig. '7, the latching-abutment 85 is in a position to be engaged by the left portion of the forward face of the crosshead 3| when the action-slide again moves forwardly.

As the breech-bolt I8 moves rearwardly as above described, it will rock the. hammer 62 rearwardly and cause the lower rear portion of its arm 6| to engage-with and cam the secondarysear 5| rearwardly against the tension of its searspring 51, since at this time the marksman will be maintaining the trigger 53in its pulled position, as is especially well shown in Fig. 8.

i The downward swinging movement of the arm 6| "ofcthe hammer 62 past the upper end of the secondary-sear 5| as above described, will place the upwardly-facing cocking-abutment 60 on the said arm in a position slightly below the downwardly-facing cocking abutment 59 of the secondary-sear 5|, so that the said hammer 62 will cocking of the hammer 62, the action-slide I! will start forwardly under the urge of the breechclosing spring 40 and will draw the said breechbolt forwardly, to pick up a fresh cartridge from any suitable magazine 'in a manner commonin the art. j

As the action-slide I9 moves forwardly as above described, theleftv portion of its forward face of its crosshead 3| will engage with the latchingabutment 85 at the forward end of the timing-bar I2, with the effect of pulling the said timing-bar forwardly against the tension of the timing-spring 16 as is shown in Fig. 5. 7

As the breech-bolt I8 reaches the limit of it forward movement under theforce supplied by the action-slide I9, the respective rear faces of the locking-lugs 20 and 2| of the saidbreech-bolt, will be brought into registry with the'forwardlyfacing locking-abutments 23 and 25 of the receiver I5. As soon as this registration occurs, the surfaces of the cam-recess 2! in the rear end of the action-slide I9, will cause the breechb-olt I8 to turn in a counterclockwise direction (as viewed from thefront) to thus engage the locking-lugs 20 and 2| with the locking-abutments 23 and 25 respectively.

As the action-slide I9 approaches thelimit'of its forward movement, pulling with it the timingbar I2, the inclined releasing-surface 85 of the said timing-bar will engage with the releasing,- surface 81 of the cylinder-lug 36 (see Fig. 5) .to

. flex the forward portion of the said timing-bar be held in its cocked position when the breechbolt I8 again moves forwardly.

.After the breech-bolt I8 has moved rearwardly to the limit of its movement to effect the rei2 outwardly. Ultimately, the forward portion of the timing-bar will be flexed outwardly sulficiently to completely disengage its rearwardlyfacing latching-abutment 86 from'the crosshead 3| of the action-slide, to thus permit the said timing-bar 12 to be snapped rearwardly by the action of the previously-compressed timingspring 16. The release of the timing-bar I2 as just described will not take place, however, until after the breech-bolt I8 has been locked, asbefore.

described. 7

When the timing-bar I2 issnapped rearwardly by the timing-spring 16, its rear end will ultimately strike the forward face of the left arm 45 of the sear-actuating lever 44, to force the same rearwardly and thus cause the entire lever 44 to swing about its pivot-pin 48 against the tension of the breech-closing spring 40 which is thrusting rearwardly against the forward face of the right arm 43 all as shown in Fig. 6.

The swinging movement of the sear-actuating lever 44 as above described, will cause its depending tripping-finger 50 toswing the upper end of the secondary-sear 5| rearwardly. The rearward movement of the secondary-sear 5| as just described will retire its downwardly-facing cockingabutment 59 out of the path of movement of the upwardly-facing cocking-abutment 60 of the hammer 62 and thus release the said hammer to forward swinging movement, to thus again effect the discharge of the firearm and the repetition of the cycle of operation above described until such time as the supply of cartridges is exhausted or until the marksman releases rearwarddraft upon the trigger 53.

Following the rocking of the sear-actuating lever 44 by the impact of the timing-bar T2, the said lever will swing back into its normalposition (see Figs. 5 and 7) under the urge of the breechclosing spring 40 and against the relativelyweaker tension of the timing-spring I6,

When the marksman releases rearward draft upon the trigger 53, the sear-arm 61 thereof will swing 'r'e'arw'a'rdly and thus interpose it's down wardly-faci'ng cockin-g abutrhent 66 in the path of movement of the upwardly-'acing cockingabutment 55, to thus restrain the hammer in its cocked position until such time as the hammer 53 is again intentionally pulled rearwardly.

The so-called timing-bar 72 requires a meets-- urable period of time to inove rearwardly when it is unhooked from the action-slide as above described, and this interval may be varied to. meet various requirements for -rates-of'-fire b suitably proportioning any or bothfof the mass of the said timing-bar or its equivalent, and the tension of the timing-spring 76 or its equivalent.

' semiautomatic operation when it isdesired tohave the firearm function as a semiautomatic firearm; theselector-lever ?8 will be turned so that its finger-piece is-projects rearwardly as indicated by broken lines in Figs.

3 and 4 instead of forwardly as indicated by full 5 lines in the same figures. This turning movement of the selector-lever l8iwili swing the eccentric-finger 8! at the-lower end of its stem i1, outwardly to thus spring the forward end of the timing-bar '12 outwardly into the position in which it is shown in Fig. 13. In'the position just referred to, the hook 84 at the front of the timingbar '52 will be swung outwardly sufiiciently so that its rearwardly-facing latching-a'butment 85 wiil not be engaged by the crosshead 3! of the action slide l 9 as the same reciprocates.

Now when the firearm is. discharged, the action-slide 19. will be drivenrearward-ly and the breech-bolt will be unlocked and moved rearwardly in a manner corresponding to that described in connection with the full automatic operation of the firearm. Thev hammer 62 will also. be swung rearwardly and in the events-as is usually the case-that the marksman has not had time to release rearward draft upon the trigger 53, the said hammer 62 will be caught and held in its cocked position by the secondary-sear 5| as illustrated in Fig. 8.

As the action-slide moves,. the timing-bar 12.,

will be in no way affected, nor will the searactuating lever 4Q, so that there will be nov automatic discharge of the firearm. l

As soon as the marksman releases rearward draft upon the trigger, 53, the secondary-sear iii will swing rearwardly to. disengage itself from the hammer 52 but not before the sear-arm 6.? of the trigger 53 has moved rearwardly into a position wherein its downwardly-facing co'cicihg abutment 6.5 is interposed in the path of movement of the upwardly-facing; cockingabutment 65- of the hammer t2. When the trigger has been fully released, the hammer 52 will swing a short dis It is to be noted that while, in the particular embodiment of the invention as shown; the tim ing bar is latched to the actibii-slide; the said timing bar is in sear arm $1 of the said trigger from the hammer effect latched to the mean bolt through the intermediary of the said action slide since the latter may properly be viewed as part of the breech-bolt assembly. 7

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential 'charac teristics of the invention, and the present embodiments are, therefore to be cbhside'red in all respects as illustrative and'notrestrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

1. An automatic firearm including in combina; tion; a receiver; a breech-bolt movable in the said receiver; an action-slide movable lengthwise of the fir'earm'-'structure and oper'atjively connected to the said breech-bolt for moving the same in the said receiver, the said action-slide having a lost motion connection with the breechbolt and provided with a forwardly-facing latching-abutment; a firing-member for efiecting' the discharge of the firearm; a sear for releasable; holding the said firing-member in a cocked pesi tion; a timing-member mounted for reciprocation lengthwise of the firearm structure and carrying a latching-portion yiel'dable in a direction transverse of the firearm-structure; the said latchingportion having a abutment r'el'easably engage'able with the forwardly-iacing latching-abutment of the said action-slide; spring-means urging the said timing member rearwardly into a retired position; the said timing-member being constructed and arranged to retire the said sear when the latching abutment of the said timing-member is disengaged from the latching ab'u'trnent of said ac} tion-slide and the timing-member retires under th urge of 'the said spri'ng m eans; and releasingmeans constructed and arranged to automatically move the transversely-yielding latching-portion of the said timing-member to disengage its latch. ing-abutment from the latching-abutment'of the said action-slide when. the latter has moved the said breech-bolt substantially into its breechclosing position. 1 2, An automatic firearm including in combinationz a receiver; a breech-bolt movable in the said receiver; an action sIide operatively connected to the said breech bolt for moving the same in the said receiver and having alost-motion connection therewith; a breech-"closing spring urging the said breech bolt into its breech-closing position; a firing-member for efiecting the discharge of the firearm; a sear for releasably holding the said firing-member in a cooked position; a sear-actuating lever operatively associated with the said sear and with the said breech-closing spring and moved by the latter in a direction counter to the movement imparted to it by the hereinafter-mentioned timing-member; atimingmember having a latching portion releasably connectible to the said action-slide for m'ovingthe timing-member therewith during the movement of the said breech-bolt from its retired position to its breechecl'osing position; spring-means urging the said timing-member in a direction opposite to that in which it is i moved by the breech-closing movement of the said action-slide; the said timing-member being constructed and arranged to swing the said sear-actuating lever against the tension of the said breech-closing springt'o cause the said lever to retire the said sear when the, latching:

' portion of the said timing m'ember is disengaged rearward'l-y-facing latchingtion: a receiver; a breech-bolt movable in the said receiver; an action-slide operatively connected to the said breech-bolt for moving the same in the said receiver and having a lost-motion connection therew th: a breech-closing spring urging the said breech-bolt into its breech-closing position; a firing-member for effecting the discharge of the firearm; a sear for releasably holdingvthe said firing-member in a cocked position; a searactuating lever operatively associated with the said sear and with the said breech-closing spring and moved by the latter in a direction counter to the movement imparted to it by the hereinaftermentioned timing-member; a timing-member having a latching-portion releasably connectible to the said action-slide for moving the timingmember therewith during the movement of the a said breech-bolt from its retired position to its breech-closing position; manually-operable selector-means constructed and arranged to selectively render the latching-portion cf the said timingmember operative or inoperative; spring-means :5

urging the said timing-member in a direction opposite to that in which it is moved by the breech closing movement of the said action-slide; the said timing-member being constructed and arranged to swing the said sear-actuating lever against the tension of the said breech-closing spring to cause the said lever to retire the said sear when thelatching-portion of the said timingmember is disengaged from the said action-slide and it retires under the urge of the said springmeans; and releasing-means constructed and arranged to automaticall disconnect the latching-portion of the said timing-member from the said action-slide when the latter has moved the said breech-bolt substantially into its breeche closing position. V

4. An automatic firearm including incombina tion; a receiver; a breech-bolt movable in the said receiver; an action-slide movable lengthwise of the firearm-structure and operatively connected to the said breech-bolt for moving the same in the said receiver, the said action-slide having a lost-motion connection with the breech-,

bolt; a breech-closing spring urging the said breech-bolt into its breech-closing position; a firing-member for effecting the discharge of the firearm; a sear for releasably holding the said firing-member in a cocked position; a searactuating lever operatively associated with the said sear and with the said breech-closing spring and moved by the latter in a direction counter to the movement imparted to it by the hereinaftermentioned timing-member; a timing-member mounted for reciprocation lengthwise of the fire arm-structure and having a latching-portion releasably connectible to the said action-slide for moving the timing-member forwardly therewith during the forward movement of the said actionslide; spring-means urging the said timing-member rearwardly for engagement with the said sear-actuating lever; the said timing-mernber being constructed and arranged to swing the said sear-actuating lever against the tension of the said breech-closing spring to cause the saidlever to retire the said sear when the latching-portion of the said timing-member is disengaged from the said action-slide and the timing-member retires under the urge of th said spring-means; and releasing-means constructed and arranged to automatically disconnect the latching-portion of the said timing-member from the said actionslide when the latter has moved the said breech bolt substantially into its breech-closing position;

5. An automatic firearm including in combination: a receiver; a breech-bolt movable in the said receiver; an action-slide movable lengthwise of the firearm-structure and operatively connected to the said breech-bolt for moving the same in the said receiver, the said action-slide having a lostmotion connection with the breech-bolt and provided with a f orWardly-facing latching-abutment; a firing-member for effecting the discharge of the firearm; a sear for releasably holding the said firing-member in a cocked position; a timingmember mounted for reciprocation lengthwise of the firearm-structure and having a flexible forward portion providedvwith a rearwarclly-facing latching-abutment releasably engageable with th forwardly-facing latching-abutment of the said action-slide; spring-means urging the said timing-member rearwardly; the said timing-member being constructed and arranged to effect the retirement of the said sear when its latching-abutment is disengaged from the latching-abutment of the action-slide and the timing-member moves rearwardly under the urge of the said springmeans; and releasing-means constructed and arranged to automaticallyfiex the forward portion of the timing-member and disengage the latch-, ing-abutment of the timing-member from the 6. An; automatic firearm including in combination a receiver; a breech-bolt movable in the said receiver; an action-slide movable lengthwise of 'the firearm-structure adjacent one side thereof and operatively connected to the said breech-bolt for moving the same in the said receiver, the said action-slide having a lost-motion connection with the breech-bolt; a firing-member for effecting the discharge of the firearm; a sear for releasably holding the said firing-member in a cocked position; a sear-actuating lever operatively associated withthe said sear and mounted for turning movement about a substantially-vertical axis; a longitudinal breech-closing spring having its forward portion thrusting forwardly upon the said actionslide and having its rear end thrusting rearwardly upon the adjacent end of the said sear-actuating lever; a timing-member mounted for reciprocation lengthwise of the firearm-structure adjacent theside thereof opposite from the said actionslide and having a latching-portion releasably connectible to the said action-slide for moving the timing-member forwardly therewith during the forward movement of the said action-slide; spring-means urging the said timing-member rearwardly into engagement with the end of the said sear-actuating lever opposite the end thereof engaged by the said breech-closing spring; the said timing-member being constructed and'an ranged to engage with and swing the said searactuating lever against the tension of the said breech-closing spring to cause the said searactuating lever to retire the said sear when the latching-portion of the said timing-member is disengaged from the said action-slide and the timing-member retires under the urge of the said spring-means; and releasing-means constructed:

13 14 and arranged to automatically disconnect the latching-portion of the said timing-member from UNITED STATES PATENTS the said action-slide when the latter has moved Number Name ate the said breech-bolt substantially into its breech- 618,743 v an J an. 1899 closing position. 5 905,071 Heinemann Nov. 24, 1908 DAVID M. WILLIAMS. 2,21 ,470 Johnson Sept. 24, 1940 2,335,688 Moore Nov. 30, 1943 2,372,327 Joyce Mar. 27, 1945 REFERENCES CITED 2,375,721 Woodhull May 3, 1945 The following references are of record in the 10 file of this patent: 

